Updated Covid boosters show meaningful protection against severe outcomes
A large study of US veterans provides fresh evidence that the updated 2024-2025 Covid vaccines continue to offer protection against serious illness, hospitalizations, and even death. Conducted amid widespread use of the Moderna and Pfizer/BioNTech mRNA vaccines, the study adds to the growing body of data suggesting that vaccines remain a valuable tool, even as the virus evolves and overall risk has declined since the pandemic’s peak.
The research, published in The New England Journal of Medicine, tracked more than 300,000 veterans who received both a 2024-2025 Covid booster and a flu shot, or only the flu shot. The analysis focused on outcomes within six months after infection, providing a real-world look at how the updated vaccines perform in a middle-aged and older population with substantial medical histories.
What the study found
Among veterans who received the Covid booster in addition to the flu vaccine, several important differences emerged when compared with those who received only the flu shot. Over six months, the boosted group experienced:
- About 29% fewer emergency department visits
- Approximately 39% fewer hospitalizations
- Around 64% fewer deaths
These reductions persisted across age groups and did not depend heavily on the presence of chronic health conditions, suggesting broad, real-world benefit from the updated vaccines.
Why the absolute benefit appears smaller now
Experts note that while the relative protection remains meaningful, the absolute benefit is smaller today than in the pandemic’s earlier phases. The circulating strains were generally milder at the time of the study, and prior infections and previous vaccinations have boosted overall immunity. As a result, the incidence of severe Covid is much lower, which translates into fewer preventable hospitalizations and deaths.
Interpreting the results for policy and public health
Dr. Jesse Goodman, an immunology expert not involved in the study, said the findings indicate that vaccines still offer meaningful protection against significant outcomes. “The vaccines are still providing additional, not perfect, protection against meaningful outcomes, including hospitalization and death, even though such severe outcomes are now much less common overall than early in the pandemic,” he noted.
NEJM editor-in-chief Dr. Eric Rubin acknowledged that the extra protection is modest in absolute terms given current risk levels. He emphasized that the study represents observational data, not a randomized trial, and therefore cannot definitively prove causation. Yet, he and others stressed that the overall evidence supports continued vaccination as a reasonable public health option for eligible populations, especially older adults with comorbidities.
What this means for individuals
For a typical middle-aged or older adult navigating decisions about Covid vaccination, the study reinforces that updated boosters can still lower serious outcomes if one contracts the virus. The benefit appears to extend across a broad spectrum of patients and is particularly relevant for those with higher baseline risk. As with all vaccines, individual risk considerations, eligibility, and local guidance should guide decisions.
The findings come as vaccination campaigns continue to evolve with the virus. Public health officials encourage high uptake of boosters alongside other preventive measures to maintain protection against severe disease in populations at greater risk.
Source: The New England Journal of Medicine; commentary from immunology and infectious disease experts
